Rotary shaft drive solenoid including a chain connector



Dec. 15, 1964 A. GERSTENFELD 3,161,791

ROTARY SHAFT DRIVE SOLENOID INCLUDING A CHAIN CONNECTOR Filed April 4, 1962 FIG. 2.

INVENTOR ARTHUR GERSTENFELD EM, a4 54;?

ATTORNEYS.

United States Patent 3,161,791 ROTARY SHAFT DRIVE SOLENOID INCLUDING A CHAIN CONNECTQR Arthur Gerstenfeld, Great Neck, N.Y., assignor, by mesne assignments, to Heinemann Electric Company, Trenton, NJ., a corporation of New Jersey Filed Apr. 4, 1962, Ser. No. 185,130 1 Claim. (Q1. 310-23) This invention relates in general to a solenoid, and more particularly to an improved rotary shaft drive solenoid of the type disclosed in a co-pending application Serial No. 99,263, filed March 28, 1961.

The general object of the present invention is to provide a new and improved rotary shaft drive solenoid of simple inexpensive design and construction.

Still another object of the present invention is the provision of a new and improved rotary shaft drive solenoid which can be constructed to yield different torque versus shaft position characteristics for different types of applications.

Still another object of the present invention is the provision of a new and improved rotary shaft drive solenoid having an output shaft which will exert a large starting torque when the solenoid is actuated.

Yet a further object of the present invention is the provision of a new and improved rotary shaft drive solenoid having a rotatable output shaft which is caused to rotate without imparting thereto any linear movement.

The instant invention is directed to a specific improvement over the rotary shaft drive solenoid disclosed in the above mentioned co-pending application S.N. 99,263, now Pat. No. 3,110,826, i.e., an improved device for translating movement of a solenoid into oscillating motion of a shaft. In the mentioned co-pending applica tion the solenoid comprises a hollow cylindrical winding with an armature or plunger disposed centrally thereof for reciprocal movement therein, cooperatively associated with the armature within the solenoid is a rotary shaft normally biased to a predetermined position. In the mentioned application the reciprocal movement of the armature imparts a rotary movement to the shaft through the means of a flexible band or tape connected at one end to the plunger, and having its other end wrapped about the shaft. Thus when the armature is moved away from the shaft upon. energization of the winding, it pulls the flexible band along with it, causing the portion of the band wound about the shaft to unwind and thereby effect rotation of the shaft.

In further experimentation, it has been discovered that a link chain or roller chain connector between the shaft and the armature greatly improved the operation of the solenoid. By utilizing a chain connection between the armatureand the rotating shaft as disclosed herein, it has been found that the chain provides maximum strength with minimum stresses being imposed thereon. Since the chain is formed with a series of pivoted points, bending stresses are minimized and consequently fatigue of the chain connector is practically eliminated. This thus insures the solenoid a longer, useful and more trouble-free life thereon. A further notableimprovement which isattributed to the chain connection of this invention resides in the provision that the chain will not collapse or tend to override or unwind due tothe angular velocity imparted to the shaft. Thus the chain connector provides for more positive response of the rotary shaft upon actuation of the reciprocal movement of the armature, i.e. the chain connector will not tend to override the angular movementof the shaft, andthus will unwind in a relationship proportional to the linear movement of the plunger.

In accordance with this invention, the chain is wrapped 3,161,791 Patented Dec. 15, 1964 around the shaft with one end of the chain secured to the shaft, and the other end secured to the plunger. When the plunger moves away from the shaft in a rectilinear manner, it will pull the chain along with it, causing the chain wound about the shaft to unwind in more direct relationship to the linear movement of the armature and thereby effect a controlled rotation of the shaft against its normal bias.

By shaping the surface contour of the shaft in the area of engagement with the chain, the torque characteristic of the solenoid can be adjusted. For instance, if the surface contour of the shaft is shaped so that the point of engagement of the chain with the shaft when the shaft is in its normal position is fairly remote from the axis of rotation of the shaft, upon energization of the solenoid there will be a relatively long lever arm through which the force exerted on the shaft by the chain operates to thereby yield a relatively large starting torque to eliminate the usual small starting torque present in rotary solenoids.

A feature of this invention resides in the provision of a chain connector which is not influenced by bending stresses for effecting rotation of the shaft. A further feature resides in the provision that the chain connection provides for a more controlled rotation of the shaft.

The above and other objects, characteristics and features of the present invention will be more fully understood from the following description taken in connection with the accompanying illustrative drawing.

In the drawing:

FIG. 1 is an end view of a solenoid embodying the present invention;

FIG. 2 is a sectional View taken along the line 22 of FIG. 1 and showing the solenoid in its energized or actuated condition;

FIG. 3 is a sectional view taken along the line 33 of FIG. 2;

FIG. 4 is a sectional view similar to FIG. 2, but showing the solenoid in its deenergized or'normal condition; and 7 FIG. 5 is a sectional view taken along the line 55 of IG. 4.

Referring now to thedrawing in detail, a solenoid embodying the present invention is generally designated therein by the reference numeral Iii. The solenoid in put leads 14, a plunger or armature 16 slidably dispose-d within a low friction tube 18 which defines the core of the coil, an output'shaft 20 rotatably mounted in bearings 22 and 24 which bearings are supported by a bearing holder or block 26. The shaft 20 is connected to the armature 16 by a flexible chain or chain-like element 28a for imparting motion to the output shaft 2% in response to motion of the plunger 16. The output shaft 20 is biased to its normal position by a spring 30 and the norinal position is determined by complementary stops 32 and 34. Surrounding the coil in closing relation therewithis a housing 36 which is secured to the bearing support or block 25 as by a screw 38. The opposite end of the solenoid is'enclosed by a cover plate 4%whichjs seated in a depression in the bearing block. In order to increase the magnetic flux density passing through the plunger 16, a conical stop made of magnetic material is provided,.which conical stop is designated by the reference character 42. If desired, a suitable mounting bracket 44 may be secured to the housing 36 as, for example, by welding, and the mounting bracket 44 may have provision for threadedly supporting two screws 46 which may be secured to any suitable plate or the like.

Referring to the Winding 12, this winding is formed inthe shape of a hollow cylinder with sleeve 18 frictional- W 1y disposed Within the central passage therein. The

sleeve 18 is preferably made of a low friction non-magnetic material such as brass to provide a low friction seat for the armature or plunger 16. It will be seen that the face of the armature or plunger 16 confronting the conical stop 42 is shaped as a hollow or concave cone complementary to the convex conical surface 48- of the conical stop 4-2, whereby the confronting surface area of the conical stop and of the plunger is relatively large to increase the magnetic attraction between them when the coil 1-2 is energized. Naturally, both the conical stop 42 and the plunger 16 are made of magnetic material whereby to greatly increase the magnetic forces present when the coil 12 is energized.

The chain-like element 23a for connecting the plunger 16 to the rotary output shaft 20 is made of a series of interconnected links. Alternately, the chain 28a may be formed of links which are pivoted together by means of connecting pins permitting each link to be individually pivoted relatively to the connected adjacent link. As an alternate construction, a bead-type chain may be employed. With any of the chain constructions, the chain element 23a, as shown in the drawings, is secured to the plunger 16 by a pin 50 extended through either the end link or an eyelet piece connected to the end link. However, it will be appreciated that any suitable securing means may be utilized in lieu thereof, e.g. welding, brazing and the like.

The chain 28a extends away from its area of securement to the plunger longitudinally of the plunger and tangentially of the output shaft 20 into engagement therewith about which it is wrapped, the other end of the chain being secured to the surface of the output shaft in any suitable fashion such as, for instance, a pin 52. Thus it will be seen that as the plunger moves from its normal or deactuated position as shown in FIGS. 4 and 5, to its actuated or energized position as shown in FIGS. 2 and 3, the chain 28a will move to the left and thereby rotate the output shaft 20 in a clockwise direction as viewed in FIGS. 3 and 5.

In order to reduce friction within the solenoid, the output shaft 20 is mounted in low friction bearings 22 and 24 supported by the bearing block 26. As shown herein the output shaft 2i extends outwardly of the solenoid at both sides thereof. Naturally, if desired, the output shaft could be arranged to extend out of one side only, the other end of the shaft being disposed within a bearing which would then act as a thrust bearing as well as a rotary bearing.

To prevent longitudinal movement of the output shaft 20 the shaft is provided with grooves 54 adjacent the exterior surfaces of the bearings 22 and 24 which grooves are adapted to receive snap rings 56 which serve to eliminate longitudinal movement of the shaft.

It will be noted that longitudinal movement of the output shaft 21 is eliminated with the construction disclosed herein due to the fact that the rotation of the shaft is not dependent upon longitudinal movement thereof as in prior art devices.

Heretofore, in rotary shaft drive solenoids, in order to effect rotation of the output shaft, the output shaft was connected to the plunger in such a fashion that the plunger and the shaft would move reciprocably together. To impart the rotary movement to the output shaft in prior art devices,-some track, usually in the form of a helix, is employed so that as the shaft is moved linearly, the interengagernent between the track and the shaft would impart rotary movement. However, the linear movement of the shaft is often undesirable asit must be compensated for in the connection between the shaft and the device being rotated thereby. The means for efiectuating this compensation often took up valuable space and, further, space had to be provided for movement of the output shaft itself.

vention elfectuated by applying a pure rotary moment to With the rotation of the output shaft in, the present inthe output shaft through the means of the chain 28a, there is no linear movement whatsoever of the output shaft 2t). Thus no provision must be made to compensate for such movement and the size of the package can thereby be reduced. It is to be further appreciated that 'the chain type connector 23a is not influenced by bending stresses.

it will further be noted that the degree of rotation of the output shaft is dependent solely on the length of the periphery of the shaft contacting the chain 28a, and on the stroke of the plunger 16. For a given shaft, the degree of rotation is dependent solely on the length of the plunger stroke. Hence for a very small increase in the length of the solenoid 10, which increase is due to the increase in stroke length of plunger 16, a substantial increase in the rotation of shaft 20 can be effected. With a solenoid of the design and construction described and illustrated herein rotation of the shaft 20 a full 360 can be achieved, and even larger rotations are possible.- Smaller amounts of rotation of the order of 90 to 180 are likewise easily attainable. The only modification other than the change in plunger stroke necessary to increase the amount of rotation is the angular distance that the chain 28a is wrapped around the shaft 20. It will be apparent that the minimum amount of wrap necessary must be equal to the angular distance of rotation of the shaft Ztl.

Still another characteristic of a solenoid embodying the present invention and particularly embodying the feature of the chain 28a imparting rotary motion to the shaft 20, is that the solenoid can be readily designed to rotate on its positive stroke either clockwise or counterclockwise. The choice of direction of rotation is dependent solely on which way the chain 28a is wrapped around the shaft 20. As viewed in FIG. 5, if the chain 28a is wrapped around the shaft 20 in a counterclockwise direction then the shaft will rotate clockwise on the positive stroke. Conversely, if the chain 28a is wrapped around the shaft 20 in a clockwise direction, then the shaft 20 will rotate in a counterclockwise direction on the positive stroke. Naturally, 'in eifectuating the desired direction of rotation of the shaft 20 on the positive stroke, consideration must be given to the placement of the steps 32 and 34 so that they will not interfere with such rotation.

Another advantage which stems from the fact that shaft 20 moves only in a rotary fashion, there being no axial movement, is that the plunger may be permitted to move much greater distances. than the prior art devices whereby to increase the efiiciency of the solenoid. A study of the characteristics of plunger magnets will demonstrate that the maximum work can be achieved only with a substantial stroke. With prior art devices which yielded rotation of the output shaft only as a result of axial movement thereof, the length of the stroke had to be kept at a maximum in order to reduce the amount of axial displacement of the output shaft. Thus the work done by t such a solenoid was intentionally kept quite small fora given magnet. However, with the present construction, the magnet plunger 16 can be permitted to move a substantial distance since such movement does not cause a concomitantaxial displacement of the output shaft but, instead, is converted into pure rotary movement of such shaft. Hence, for a given magnet a far more efficient solenoid canbe constructed. This increase in eificiency can manifest itself either in a smaller magnet (which would result in a smaller solenoid of lighter weight) or in a reduction in power input for a given magnet, or a sole-- noid having the same size'magnet with the same input but a far increased output. Naturally a combination of these advantages canbe achieved byproper design.

As stated hereinbefore, the output shaft 20 is biased to a normal position by a spring 3%. The spring 30 is secured to the shaft by being wrapped around: stop 32 which. is pressed fit into shaft 20, the spring then being wound several times around the output shaft and having its other end anchored to the bearing block 26 by being wrapped around stop 34 pressed fit into such bearing block. The spring serves to bias the shaft 210 to a position in which the stops 32 and 34 engage to thereby prevent further rotation. in this position, the connecting chain 28a has pulled the armature 16 away from the conical stop 43 to leave an air gap 53 thereoetween. This condition is shown in FIGS. 4 and 5. When energy is supplied to winding 12 through input leads 14, a magnetic field will be established which sets up an attractive force between the stationary conical stop l2 and the slidably movable armature 16. This force is sufficient to overcome the force exerted by the spring 30 through the chain on the armature 116 to thereby cause the armature to move to the left until it engages the conical stop. This movement of the armature to the left will pull the connecting chain 2&1 to the left and thereby serve to rotate the output shaft in the clockwise direction. The energized condition of solenoid l is shown in FIGS. 2 and 3. The rotation of the output shaft 2i? can be employed to operate any of a large number of devices. Upon the energy supply being discontinued to the winding 12, the magnetic field collapses to thereby substantially eliminate the magnetic attractive force between the conical stop 42 and the armature Accordingly, the force exerted by the spring on the output shaft 20 is sufficient to rotate the output shaft in a counterclockwise direction until the stop 32 engages the stop 34 at which point further rotary movement of the shaft will be prevented. This counterclockwise rotation of the output shaft 2% will pull the connecting chain 234: to the right as viewed in the drawings and thereby pull the armature if to the right to restore it to its normal or deenergized position as shown in 4 and 5.

One of the critical characteristics in considering rotating shaft drive solenoids is the torque characteristic of the output shaft. lt fundamental that torque is equal to a twisting force times the lever arm through which the force operates. It is also basic and well known that the magnetic attraction between two parts is dependout upon the spacing between such parts and the greater the spacing the less the magnetic attraction. Thus it will be seen that most rotary shaft drive solenoids which depend upon the magnetic attraction between two relative ly movable parts would have low starting torque due to the fact that the initial attraction between a movable plunger and a fixed magnetic slug would be relatively small as compared with the force at the end of the stroke. Because of the manner of connecting plunger 16 with rotary shaft 29 in applicants rotary solenoid, which manner, as hereinbefore described, is the chain this variation in force exerted by the plunger on the shaft can be compensated for. The compensation takes the form of shaping the contour of the shaft 20 in the vicinity where the chain 28a is wrapped around a portion of the surface of the shaft 2%.

As shown herein the surface of the shaft 20 under lying the chain 28a is shaped much like a cam. The shape is such that when the shaft is in its normal or deenergized position with the stops 32 and 34 in stopping engagement, the chain 2% engages a high contour portion (ill of the shaft 26 so that when chain 28a exerts a force on the shaft 20 due to the attraction of the plunger 16 to the conical stop 42 by the actuation of the coil 12, the force is exerted through a relatively large lever arm. This will increase the amount of starting torque to thereby overcome the initial or static friction resisting rotation of the shaft 20. However, once the shaft 20 starts to rotate and the plunger 16 moves closer to the conical stop 4-2, the frictional forces decrease and the force exerted by the plunger increases. At this point, the lever arm through which the chain 28a operates to exert a turning force on the shaft 20 can be decreased and this decrease can be effected by reducing the diameter of the shaft in the area of contact during this portion of the stroke or" the plunger. This is done by tapering off the high portion on at an appropriate point on the shaft relative to the chain 23a. At the completion of the stroke the chain will be engaging the low part as of the shaft surface contour to thereby reduce the lever arm and hence maintain the torque at substantially constant value.

it will therefore be seen that by a proper selection of the surface contour of the shaft 20 a substantially uniform torque can be applied to the output shaft by the chain 28a working through a variable lever arm. Likewise, any other torque characteristic can be built in to my novel rotary solenoid by a proper contouring of the shaft 20 in the area of engagement with the chain 280:.

The solenoid lil illustrated in the drawing is adapted to operate in response to energization by a DC. source. However, the principle involved in the construction of the solenoid are equally applicable to AC. solenoids and the design changes necessary to make solenoid 10 operate in response to alternating current energy are well within the scope of persons skilled in the art.

While l have shown and described the preferred embodiment of the present invention and have suggested various modifications therein, it will be understood that other changes and modifications may be made therein within the scope of the appended claim without departing from the spirit and scope of this invention.

What l claim is:

A. rotary shaft drive solenoid comprising a hollow electrical coil a apted to be energized and deenergized, a stop of magnetic material fixed relative to said coil and disposed at least in part within said hollow coil, a plunger of magnetic material slidably disposed within said coil for movement from and to a normal or deencrgized position in which said plunger is spaced from said stop and to and from an actuated or energized position in which said plunger is in engagement with said stop, a re tatablc output shaft extending transversely of the line of movement of said plunger for rotation a predetermined angular distance from and to a irst or normal position and to and from a second or actuated position concomitantly with movement of said plunger from and to its normal position and to and from its actuated position, respectively, and a serially pivoted chain connected at one end to said plunger and at the other end to said shaft, said chain being wrapped around said shaft at least said predetermined angular distance when said shaft is in said normal position, the portion of the shaft about which said chain is wrapped being formed with high and low parts, whereby to impart said concomitant rotation to said shaft from said first to said second positions in response to movement of said plunger from its normal to its actuated position, a pair of stops one fixed to said shaft and the other fixed relative to said coil, said stops being engageable when said shaft is in said normal position for preventing rotation of said shaft away from its actuated position beyond said normal position, and a spring connected to said shaft for biasing said shaft and said plunger toward their normal positions, whereby the serially pivoted chain is under minimum stresses during the unwinding and winding from and onto the high and low parts of the shaft during reciprocation of said plunger resulting in minimum fatigue failures of the. serially pivoted chain.

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